Ultrasonic inspection device and ultrasonic inspection method

ABSTRACT

This ultrasonic inspection device, for inspecting a packaged semiconductor device, is provided with: an ultrasonic transducer which outputs ultrasonic waves to a semiconductor device; a receiver (a reflection detection unit) which detects reflected waves of the ultrasonic waves reflected on the semiconductor device; a stage which moves the positions of the semiconductor device relative to the ultrasonic transducer; a stage control unit which controls driving of the stage; and an analysis unit which analyzes the reaction of the semiconductor device to the input of the ultrasonic waves from the ultrasonic transducer. The stage control unit controls the distance between the semiconductor device and the ultrasonic transducer on the basis of a peak occurring in time waveform of the reflected wave detected by the receiver.

TECHNICAL FIELD

The present invention relates to an ultrasonic inspection device and anultrasonic inspection method.

BACKGROUND ART

As a conventional ultrasonic inspection device, there is an inspectiondevice for a semiconductor integrated circuit wiring system usingultrasonic heating described in Patent Document 1, for example. In thisconventional ultrasonic inspection device, ultrasonic waves are radiatedto a semiconductor integrated circuit which is an object to be inspectedwhile electric power is supplied from a constant voltage source.Additionally, a current image or a defect image of the semiconductorintegrated circuit is generated by detecting a change in a currentflowing through a ground wiring due to irradiation with the ultrasonicwaves.

CITATION LIST Patent Literature

[Patent Literature 1] Japanese Unexamined Patent Publication No.H8-320359

SUMMARY OF INVENTION Technical Problem

In the above-described conventional ultrasonic inspection device, asemiconductor chip taken out from a package may be an object to beinspected. However, considering the necessity of taking out thesemiconductor chip from the package and the possibility of thecharacteristics of a circuit changing at the time of taking out thesemiconductor chip, it is preferable to inspect the semiconductor devicein a packaged state. On the other hand, when a packaged semiconductordevice is inspected, since the semiconductor chip which is at anobservation point may not be able to be visually recognized from theoutside, devices for allowing the ultrasonic waves to be focused easilyon the semiconductor chip may be required.

The present invention has been realized in order to solve theabove-described problem, and an object thereof is to provide anultrasonic inspection device and an ultrasonic inspection method inwhich a focal point of ultrasonic waves is easily able to be adjustedsuch that it has a desired position on a packaged semiconductor device.

Solution to Problem

An ultrasonic inspection device according to one aspect of the presentinvention is an ultrasonic inspection device for inspection of apackaged semiconductor device, including an ultrasonic transducerconfigured to output ultrasonic waves to the semiconductor device, areflection detection unit configured to detect reflected waves of theultrasonic waves reflected by the semiconductor device, a stageconfigured to move a position of the semiconductor device relative tothe ultrasonic transducer, a stage control unit configured to controldriving of the stage, and an analysis unit configured to analyze areaction of the semiconductor device in accordance with an input of theultrasonic waves by the ultrasonic transducer, wherein the stage controlunit controls a distance between the semiconductor device and theultrasonic transducer on the basis of a peak appearing in a timewaveform of the reflected waves detected by the reflection detectionunit.

In this ultrasonic inspection device, the distance between thesemiconductor device and the ultrasonic vibrator is controlled on thebasis of the peak appearing in the time waveform of the reflected wavesdetected by the reflection detection unit. The peak of the time waveformof the reflected waves appears corresponding to the reflection of theultrasonic waves on a chip surface in the semiconductor device.Therefore, it is possible to easily adjust a focus of the ultrasonicwaves to a position of the chip in the package by controlling thedistance between the semiconductor device and the ultrasonic transduceron the basis of the peak.

Further, the stage control unit may control the distance between thesemiconductor device and the ultrasonic transducer so that the peak ofthe time waveform is maximized. Accordingly, it is possible toaccurately adjust the focus of the ultrasonic waves to the position ofthe chip in the package.

Further, the stage control unit may control the distance between thesemiconductor device and the ultrasonic transducer on the basis of anyone of peaks after a second peak which appear in the time waveform. Itis considered that a first peak appearing in the time waveform is due tothe reflected waves from a package surface of the semiconductor device.Therefore, when the chip is arranged in a single layer or a plurality oflayers in the package, the focus of the ultrasonic waves can be easilyadjusted to a position of the chip in the package by paying attention tothe peaks after the second peak which appear in the time waveform.

Further, the stage control unit may set a detection window for the timewaveform on the basis of package information in the semiconductor deviceand may detect the peak. In this case, it is possible to accuratelydetect the peaks of the time waveform in a short time.

Further, the ultrasonic inspection device may further include a powersupply device configured to apply a constant voltage or a constantcurrent to the semiconductor device, and a reaction detection unitconfigured to detect a current or a voltage of the semiconductor devicein accordance with input of the ultrasonic waves in a state in which theconstant voltage or the constant current is applied, and the analysisunit may generate an analysis image on the basis of a detection signalfrom the reaction detection unit. In this case, the inspection of thepackaged semiconductor device can be performed with high accuracy bymeasuring change in resistance in the semiconductor device caused by theinput of the ultrasonic waves.

Further, the ultrasonic inspection device may further include a signalgeneration unit configured to input a driving signal to the ultrasonictransducer and output a reference signal corresponding to the drivingsignal, and the analysis unit may generate the analysis image on thebasis of the detection signal and the reference signal. Accordingly, itis possible to further improve inspection accuracy of the packagedsemiconductor device.

Further, the analysis unit may generate a reflection image on the basisof a detection signal from the reflection detection unit. In this case,a shape of the chip in the semiconductor device can be acquired on thebasis of the reflection image.

Further, the analysis unit may generate a superimposed image in whichthe analysis image and the reflection image are superimposed. In thiscase, since analysis results based on the analysis image and the shapeof the chip in the semiconductor device are superimposed, it is easy toidentify a position of a fault and the like.

An ultrasonic inspection method according to one aspect of the presentinvention is an ultrasonic inspection device for inspection of apackaged semiconductor device, including an adjusting a focal positionof ultrasonic waves output from an ultrasonic transducer with respect tothe semiconductor device, and an analyzing a reaction of thesemiconductor device in accordance with input of the ultrasonic waves,wherein, in the adjusting, reflected waves of the ultrasonic wavesreflected by the semiconductor device is detected, and a distancebetween the semiconductor device and the ultrasonic transducer isadjusted on the basis of a peak appearing in a time waveform of thereflected waves.

In the ultrasonic inspection method, the distance between thesemiconductor device and the ultrasonic transducer is adjusted on thebasis of the peak appearing in the time waveform of the reflected wavesdetected by the reflection detection unit. The peak of the time waveformof the reflected waves appears corresponding to the reflection of theultrasonic waves on the chip surface in the semiconductor device.Therefore, it is possible to easily adjust the focus of the ultrasonicwaves to the position of the chip in the package by controlling thedistance between the semiconductor device and the ultrasonic transduceron the basis of the peak.

In the adjusting, the distance between the semiconductor device and theultrasonic transducer may be adjusted so that the peak of the timewaveform is maximized. Therefore, it is possible to accurately adjustthe focus of the ultrasonic waves to the position of the chip in thepackage.

In the adjusting, the distance between the semiconductor device and theultrasonic transducer may be adjusted on the basis of any one of peaksafter a second peak which appear in the time waveform. In this way, whenthe chip is arranged in a single layer or a plurality of layers in thepackage, the focus of the ultrasonic waves can be easily adjusted to theposition of the chip in the package.

In the adjusting, a detection window for the time waveform may be set onthe basis of package information in the semiconductor device, and thepeak may be detected. In this case, it is possible to accurately detectthe peak of the time waveform in a short time.

Advantageous Effects of Invention

According to the present invention, it is possible to easily adjust afocal point of ultrasonic waves to a desired position in a packagedsemiconductor device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram showing an embodiment of anultrasonic inspection device.

FIG. 2 is a schematic diagram showing a configuration of an ultrasonictransducer.

FIG. 3 is a schematic diagram showing a focal position of ultrasonicwaves at the time of inspection execution.

FIG. 4 is a diagram showing an example of control of adjustment of thefocal position of the ultrasonic waves.

FIG. 5 is a diagram showing a process subsequent to that of FIG. 3.

FIG. 6 is a diagram showing another example of adjustment of the focalposition of the ultrasonic waves.

FIG. 7 is a diagram showing an example of an analysis image.

FIG. 8 is a diagram showing an example of a reflection image.

FIG. 9 is a diagram showing an example of a superimposed image.

FIG. 10 is a flowchart showing an example of an operation in theultrasonic inspection device shown in FIG. 1.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a preferred embodiment of an ultrasonic inspection deviceand an ultrasonic inspection method according to one aspect of thepresent invention will be described in detail with reference to thedrawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of anultrasonic inspection device. The ultrasonic inspection device 1 is adevice for inspecting a semiconductor device D as an object to beinspected while keeping the semiconductor device D in a packaged state.The ultrasonic inspection device 1 is configured as a device fordetermining the presence or absence of faults in the packagedsemiconductor device D and identifying a position of a fault on thebasis of a method of measuring change in resistance in the semiconductordevice D caused by an input of ultrasonic waves W.

One surface side of the semiconductor device D is an inspection surfaceDt to which the ultrasonic waves W are input. The semiconductor device Dis held by a holding plate or the like in a state in which theinspection surface Dt faces downward. The semiconductor device D may bea separate semiconductor element (discrete) including diodes, powertransistors or the like, an optoelectronic element, a logic large scaleintegration (LSI) constituted by a sensor/an actuator or a transistorhaving a metal-oxide-semiconductor (MOS) structure or a bipolarstructure, a memory element, a linear integrated circuit (IC), a hybriddevice thereof, and the like. Further, the semiconductor device D may bea package including a semiconductor device, a composite substrate, orthe like.

As shown in FIG. 1, the ultrasonic inspection device 1 includes anultrasonic transducer 2, a stage 3, a pulse generator (a signalgeneration unit) 4, a reaction detection unit 5, a lock-in amplifier (afrequency analysis unit) 6, a computer (an analysis unit) 7, and amonitor 8.

The ultrasonic transducer 2 is a device which inputs the ultrasonicwaves W to the semiconductor device D. As shown in FIG. 2, theultrasonic transducer 2 has a pulser 11 and a medium holding unit 12.The ultrasonic transducer 2 has, for example, a tubular shape, morespecifically, a cylindrical shape. A tip end surface 2 a of theultrasonic transducer 2 is a portion which outputs the ultrasonic wavesW and is disposed upward to face an inspection surface Dt of thesemiconductor device D. The tip end surface 2 a actually has a concaveshape, and the ultrasonic waves W generated at respective positions onthe tip end surface 2 a have a focal point at a position a predetermineddistance away from the tip end surface 2 a. The ultrasonic waves Woutput from the tip end surface 2 a are elastic vibration waves of about20 kHz to 10 GHz, for example.

The pulser 11 is a unit which drives the ultrasonic transducer 2 on thebasis of a driving signal output from the pulse generator 4. In theembodiment, the pulser 11 also has a function as a receiver (areflection detection unit) 13 which detects the ultrasonic waves Wreflected by the inspection surface of the semiconductor device D. Thereceiver 13 detects the reflected waves of the ultrasonic waves W andoutputs a detection signal indicating a detection result to the computer7.

The medium holding unit 12 is a unit which holds a medium M between theultrasonic transducer 2 and the semiconductor device D. The medium Mheld by the medium holding unit 12 is water in the embodiment. Themedium M is not particularly limited as long as it matches an impedanceof a material used for a package of the semiconductor device D, andanother liquid such as glycerin, a gel-like or jelly-like substance, orthe like may be used as the medium M. In the embodiment, the mediumholding unit 12 has a tubular member 14 formed of a material havingsufficient flexibility and wettability with respect to the medium M,such as a silicone resin. The tubular member 14 is detachably fitted toan end 2 b of the ultrasonic transducer 2 on the side of the tip endsurface 2 a.

When the tubular member 14 is slidably fitted to the end 2 b so that apart of the tubular member 14 protrudes from the tip end surface 2 a, aholding space S for holding the medium M is formed by an innerperipheral surface 14 a of the tubular member 14 and the tip end surface2 a of the ultrasonic transducer 2. A volume of the holding space S canbe varied by adjusting a protrusion amount of the tubular member 14 fromthe tip end surface 2 a of the ultrasonic transducer 2. It is possibleto adjust a range over which the focal position of the ultrasonic wavesW output from the ultrasonic transducer 2 can be adjusted by adjustingthe protrusion amount of the tubular member 14. Accordingly, it ispossible to provide an optimum volume for the holding space S at whichthe medium M does not spill out even for semiconductor devices D havingpackages with different resin thicknesses.

Graduation markings may be provided on the tubular member 14 tofacilitate ascertaining of the protrusion amount of the tubular member14. A position at which the graduation markings are provided is, forexample, an inner peripheral surface 14 a or an outer peripheral surface14 c of the tubular member 14. The protrusion amount of the tubularmember 14 can be adjusted by manually sliding a position of the tubularmember 14 with respect to the end 2 b of the ultrasonic transducer 2 andchanging a fitting amount of the tubular member 14. The position of thetubular member 14 with respect to the end 2 b of the ultrasonictransducer 2 may be adjusted using a slide mechanism. Further, theprotrusion amount of the tubular member 14 may be adjusted by replacingthe tubular member 14 with a tubular member 14 having a differentlength, while keeping the fitting amount of the tubular member 14constant.

A medium flow port 15 for adjusting a holding amount of the medium Mheld in the holding space S is provided in a peripheral wall portion ofthe tubular member 14. A flow pipe 16 connected to an external mediumstorage unit (not shown) is inserted into the medium flow port 15 sothat an inflow of the medium. M into the holding space S and a dischargeof the medium M from the holding space S may be performed. A flow rateof the medium M is controlled by the computer 7, for example.

It is preferable that the medium flow port 15 be provided at a certaindistance from a tip end surface 14 b of the tubular member 14. Thereby,it is possible to prevent foreign matter accumulating in the vicinity ofthe tip end surface 14 b of the tubular member 14 in the holding space Seven when foreign matter is mixed into the medium M flowing in from themedium flow port 15. The ultrasonic waves W are focused on the vicinityof the tip end surface 14 b of the tubular member 14, rather than thevicinity of the tip end surface 2 a of the ultrasonic transducer 2.Therefore, accumulation of foreign matter in the vicinity of the tip endsurface 14 b of the tubular member 14 is minimized, and an influence ofinterference of the ultrasonic waves W due to foreign matter can beminimized.

Further, a level sensor (a holding amount detection unit) 17 fordetecting the holding amount of the medium M in the holding space S isdisposed at a position above the medium flow port 15 (on the side of theupper end surface 14 b) on the inner peripheral surface 14 a of thetubular member 14. The level sensor 17 outputs a detection signalindicating a detection result to the computer 7. Control of the amountof the medium M in the holding space S at the time of adjusting thefocal position of the ultrasonic waves W is performed on the basis of adetection signal from the level sensor 17. A distance sensor fordetecting a distance to the semiconductor device D may be mounted on thetubular member 14. Accordingly, interference between the tubular member14 and the semiconductor device D can be prevented when the stage 3described later is driven in a Z-axis direction.

As shown in FIG. 1, the stage 3 is a device for moving a position of thesemiconductor device D relative to the ultrasonic transducer 2. In theembodiment, the stage 3 is configured as a three-axis stage which can bedriven in X, Y, and Z-axis directions, and the ultrasonic transducer 2is fixed on the stage 3. The driving of the stage 3 is controlled on thebasis of an instruction signal from the computer 7. An input position ofthe ultrasonic waves W on the inspection surface Dt of the semiconductordevice D is irradiated by driving the stage 3 in an in-plane direction(the X and Y axis directions) of the inspection surface Dt of thesemiconductor device D.

Further, the focal position of the ultrasonic waves W is adjusted with acertain accuracy in a thickness direction of the semiconductor device Dby driving the stage 3 in the thickness direction (the Z-axis direction)of the semiconductor device D. The stage 3 may be fixed to thesemiconductor device D instead of the ultrasonic transducer 2. When theinspection of the semiconductor device D starts, as shown in FIG. 2, themedium M is supplied into the holding space S to such an extent that themedium M rises from the holding space S of the medium holding unit 12due to surface tension. Additionally, a raised portion Ma of the mediumM is brought into contact with the inspection surface Dt of thesemiconductor device D by driving the stage 3 in the thickness directionof the semiconductor device D. Therefore, a path of the ultrasonic wavesW from the tip end surface 2 a of the ultrasonic transducer 2 to theinspection surface Dt of the semiconductor device D is filled with themedium M. Additionally, as shown in FIG. 3, the stage 3 is drivenfurther in the thickness direction of the semiconductor device D, andthe focal position of the ultrasonic waves W is adjusted to be in thevicinity of a chip C in the semiconductor device D.

The pulse generator 4 is a device which inputs a driving signal to theultrasonic transducer 2. A frequency of the driving signal is set to thesame frequency as that of the ultrasonic waves W generated by theultrasonic transducer 2. As in the embodiment, when a lock-in detectionis performed using the lock-in amplifier 6, a lock-in frequency may beseparately set, and a burst signal obtained by combining a frequency forgenerating the ultrasonic waves W and the lock-in frequency may be inputto the ultrasonic transducer 2 as the driving signal. In this case, areference signal corresponding to the lock-in frequency is output fromthe pulse generator 4 to the lock-in amplifier 6. The frequency forgenerating the ultrasonic waves is, for example, about 25 MHz to 300MHz, and the lock-in frequency is, for example, about 1 kHz to 5 kHz.

The reaction detection unit 5 is a device which detects a reaction ofthe semiconductor device D in accordance with the input of theultrasonic waves W by the ultrasonic transducer 2. The reactiondetection unit 5 is configured by, for example, a detection amplifierconnected to a front stage of the lock-in amplifier 6. A power supplydevice 10 which applies a constant voltage or a constant current to thesemiconductor device D is built into the reaction detection unit 5. Thereaction detection unit 5 detects a current or a voltage of thesemiconductor device D corresponding to the input of the ultrasonicwaves W and outputs a detection signal indicating a detection result tothe lock-in amplifier 6 in a state in which the constant voltage or theconstant current is applied. The reaction detection unit 5 may extractonly an AC component and may output the detection signal.

The lock-in amplifier 6 is a device which performs a lock-in detectionof the detection signal output from the reaction detection unit 5. Thelock-in amplifier 6 performs the lock-in detection of the detectionsignal output from the reaction detection unit 5 on the basis of thereference signal output from the pulse generator 4. Additionally, thelock-in amplifier 6 outputs a detection signal indicating the detectionresult to the computer 7.

The computer 7 is physically configured by a memory such as a RAM and aROM, a processor (an arithmetic circuit) such as a CPU, a communicationinterface, a storage unit such as a hard disk, and a display unit suchas a monitor 8. Examples of the computer 7 include a personal computer,a cloud server, a smart device (such as a smartphone, a tablet terminaland the like), a microcomputer, a field-programmable gate array (FPGA),and the like. The computer 7 serves as a stage control unit 21 whichcontrols an operation of the stage 3 and an analysis unit 22 whichanalyzes the detection signal from the lock-in amplifier 6 by executinga program stored in a memory with a CPU of a computer system.

More specifically, the stage control unit 21 performs control ofadjustment of the focal position of the ultrasonic waves W in thethickness direction of the semiconductor device D and control ofradiation of the ultrasonic waves W with respect to the inspectionsurface Dt of the semiconductor device D. In the control of adjustmentof the focal position, the stage control unit 21 performs control of thestage 3 with respect to the Z direction on the basis of the detectionsignal output from the receiver 13 of the ultrasonic transducer 2. Inthe control of radiation of the ultrasonic waves W, the stage controlunit 21 performs control of the stage 3 in the X and Y directions sothat the ultrasonic waves W move along the inspection surface Dt of thesemiconductor device D. The stage control unit 21 sequentially outputsposition information of the stage 3 during the control of radiation tothe analysis unit 22.

FIG. 4 is a diagram showing an example of the control of adjustment ofthe focal position. In the example of the drawing, a horizontal axisrepresents a time (a time from the output of the ultrasonic waves W tothe detection of the reflected waves), a vertical axis represents anamplitude, and a time waveform K of the detection signal from thereceiver 13 is plotted. The time waveform K may be obtained byintegrating the detection signals of the reflected waves when theultrasonic waves W are output a plurality of times.

As shown in FIG. 4, as the focal position of the ultrasonic waves W isdisplaced toward the semiconductor device D, a first peak P1corresponding to reflection on a package surface of the semiconductordevice D appears at a certain position in the time waveform K. When thefocal position of the ultrasonic waves W is further displaced toward thesemiconductor device D from the position at which the first peak P1appears, the focal position of the ultrasonic waves W moves into thepackage of the semiconductor device D, and a second peak P2corresponding to reflection on a surface of the chip C inside thesemiconductor device D appears at a certain position in the timewaveform K, as shown in FIG. 5. Therefore, the stage control unit 21controls the position of the stage 3 in the Z-axis direction so that anamplitude of the second peak P 2 is maximized.

In the control of adjustment of the focal position, a case in which aresin thickness of the package is known or a case in which a resincomposition of the package is known and a speed of sound of theultrasonic waves W in the package can be calculated is considered. Inthis case, a range of an appearance position (an appearance time) of thesecond peak P2 may be calculated in advance on the basis of suchinformation, and a detection window A for detecting the second peak P2may be set. The detection accuracy of the appearance position of thesecond peak P2 can be improved and the detection time can be shorteneddue to the setting of the detection window A. When it is known that aplurality of layers of the chip C are built into the semiconductordevice D, the position of the stage 3 in the Z-axis direction may becontrolled on the basis of a peak after the second peak P2.

Further, since a focal depth of the ultrasonic waves W is relativelydeep, it may be difficult to distinguish a position at which theamplitude of the second peak P2 is a maximum. In this case, for example,as shown in FIG. 6, the position of the stage 3 in the Z-axis directionmay be adjusted to correspond to a central position (a central time) Tin a range in which the amplitude of the second peak P2 is a maximum.Also, the time waveform K may be differentiated, and the position of thestage 3 in the Z-axis direction may be adjusted to correspond to acentral position of a peak value of the time waveform after thedifferential processing.

The analysis unit 22 performs mapping of the detection signal outputfrom the lock-in amplifier 6 during the inspection of the semiconductordevice D on the basis of the position information of the stage 3 outputfrom the stage control unit 21 and generates an analysis image 31, asshown in FIG. 7. In the analysis image, a display luminance range, acolor, a transparency, and the like according to the reaction (an amountof change of a current or a voltage) of the semiconductor device D canbe arbitrarily set.

Further, the analysis unit 22 performs mapping of the detection signaloutput from the receiver 13 during the inspection of the semiconductordevice D on the basis of the position information of the stage 3 outputfrom the stage control unit 21 and generates a reflection image 32, asshown in FIG. 8. In generating the reflection image 32, it is preferableto extract only a time component, which corresponds to the reflectedwave from the surface of the chip C inside the semiconductor device D,in the detection signal from the receiver 13. In this way, it ispossible to obtain the reflection image 32 indicating a shape of thechip C in the semiconductor device D.

As shown in FIG. 9, the analysis unit 22 may generate a superimposedimage 33 in which the analysis image 31 and the reflection image 32 aresuperimposed. The analysis unit 22 outputs the generated superimposedimage 33 to the monitor 8. In the superimposed image 33, the reaction ofthe semiconductor device D indicated by the analysis image 31 issuperimposed on the shape of the chip C in the semiconductor device Dindicated by the reflection image 32, and a position of a fault in thechip C can be easily identified. In the reflection image 32, not onlythe shape of the chip C but also an abnormality such as separation of acircuit may be checked. Therefore, in the superimposed image 33, when anabnormal position which can be checked from the analysis image 31 and anabnormal position which can be checked from the reflection image 32 aresuperimposed, the abnormal position may be highlighted and displayed.

Next, an operation of the ultrasonic inspection device 1 will bedescribed.

FIG. 10 is a flowchart showing an example of the operation of theultrasonic inspection device 1. As shown in the drawing, when thesemiconductor device D is inspected using the ultrasonic inspectiondevice 1, first, the semiconductor device D is disposed on a holdingplate (not shown) or the like (Step S01). Next, the medium M is causedto flow from the medium flow port 15 to the medium holding unit 12, andthe medium M is held in the holding space S (Step S02). In Step S02, asdescribed above, the raised portion Ma of the medium M due to surfacetension is formed. The stage 3 is driven in the Z-axis direction so thatthe tip end surface 14 b of the tubular member 14 does not come intocontact with the inspection surface Dt of the semiconductor device D andonly the raised portion Ma of the medium M comes into contact with theinspection surface Dt of the semiconductor device D (refer to FIG. 2).

After the medium M is held, the focal position of the ultrasonic waves Wis adjusted (Step S03). Here, first, the stage 3 is driven in the X-axisdirection and the Y-axis direction so that the ultrasonic transducer 2comes to a position facing the chip C. Next, on the basis of theappearance position of the second peak P2 in the time waveform K of thereflected waves of the ultrasonic waves W output from the receiver 13,the stage 3 is driven in the Z-axis direction so that the focal positionof the ultrasonic waves W coincides with the surface of the chip Cinside the semiconductor device D (refer to FIG. 3). The adjustment ofthe focal position of the ultrasonic waves W may be automaticallyperformed by the stage control unit 21 and may be performed by a user ofthe ultrasonic inspection device 1 manually moving the position of thestage 3 while visually checking the appearance position of the secondpeak P2 in the time waveform K.

After the focal position of the ultrasonic waves W is adjusted, a stepof adjusting a tilt of the semiconductor device D may be performed. Inthis step, a posture of the holding plate or the stage 3 is adjusted sothat the time waveforms K of the reflected waves when the stage 3 isdriven uniaxially in the X-axis direction and the Y-axis directioncoincide with each other. This step may also be automatically performedby the stage control unit 21 and may be performed manually while theuser of the ultrasonic inspection device 1 visually checks the timewaveforms K.

Next, the reflection image of the semiconductor device D is generated(Step S04). In Step S04, the driving signal is input from the pulsegenerator 4 to the ultrasonic transducer 2, and ultrasonic waves W areradiated from the ultrasonic transducer 2 on the semiconductor device D.Additionally, the reflected waves from the semiconductor device D aredetected by the receiver 13, and the reflection image 32 is generated byperforming mapping on the basis of the detection signal output from thereceiver 13 and the position information of the stage 3 output from thestage control unit 21.

Next, the analysis position is checked based on the reflection image 32,the analysis of the semiconductor device D is performed, and theanalysis image is generated (Step S05). In Step S05, a constant voltage(or a constant current) is applied from the power supply device 10 tothe semiconductor device D, the driving signal is input from the pulsegenerator 4 to the ultrasonic transducer 2, and the ultrasonic waves Ware input from the ultrasonic transducer 2 to the semiconductor deviceD. Additionally, the stage 3 is driven in the X and Y-axis directions,and a change in a current or a voltage of the semiconductor device D inaccordance with the input of the ultrasonic waves W is detected at eachposition on the inspection surface Dt of the semiconductor device D. Thechange in the current or the voltage of the semiconductor device D isdetected by the reaction detection unit 5, and the detection signal fromwhich the AC component is extracted is output from the reactiondetection unit 5 to the lock-in amplifier 6. In the lock-in amplifier 6,the lock-in detection is performed based on the detection signal outputfrom the reaction detection unit 5 and the reference signal output fromthe pulse generator 4, and the detection signal thereof is output to theanalysis unit 22.

In the analysis unit 22, the analysis image and the reflection image aregenerated on the basis of the detection signal of the lock-in detection.That is, during the inspection of the semiconductor device D, themapping of the detection signal output from the lock-in amplifier 6 isperformed on the basis of the position information of the stage 3 outputfrom the stage control unit 21, and the analysis image 31 is generated.Additionally, the analysis unit 22 generates the superimposed image 33in which the analysis image 31 and the reflection image 32 aresuperimposed, and the superimposed image 33 is displayed on the monitor8 (Step S06).

As described above, in the ultrasonic inspection device 1, a distancebetween the semiconductor device D and the ultrasonic transducer 2 iscontrolled on the basis of the peak appearing in the time waveform K ofthe reflected waves detected by the receiver 13. The peak of the timewaveform K of the reflected waves appears correspondingly to thereflection of the ultrasonic waves W on the surface of the chip C in thesemiconductor device D. Therefore, the focal position of the ultrasonicwaves W can be easily adjusted to the position of the chip in thepackage by controlling the distance between the semiconductor device Dand the ultrasonic transducer 2 on the basis of the peak.

Further, in the ultrasonic inspection device 1, the stage control unit21 controls the distance between the semiconductor device D and theultrasonic transducer 2 so that the peak of the time waveform K ismaximized. Therefore, the focal position of the ultrasonic waves W canbe accurately adjusted to the position of the chip C in the package.

Further, in the ultrasonic inspection device 1, the stage control unit21 controls the distance between the semiconductor device D and theultrasonic transducer 2 on the basis of any one of the peaks after asecond peak which appear in the time waveform K. It is considered that afirst peak appearing in the time waveform K is due to the reflectedwaves from a package surface of the semiconductor device D. Therefore,when the chip C is disposed in a single layer or a plurality of layersin the package, the focal position of the ultrasonic waves W can beeasily adjusted to the position of the chip C in the package by payingattention to the peaks after the second peak which appear in the timewaveform K.

Further, in the ultrasonic inspection device 1, the stage control unit21 sets the detection window A for the time waveform K on the basis ofpackage information (a thickness, a resin composition, or the like) inthe semiconductor device D and detects the peak. Since the detectionrange is narrowed in advance by setting the detection window A, it ispossible to accurately detect the peak of the time waveform K in a shorttime.

Further, in the ultrasonic inspection device 1, the power supply device10 which applies a constant voltage or a constant current to thesemiconductor device D, and the reaction detection unit 5 which detectsthe current or voltage of the semiconductor device D corresponding tothe input of the ultrasonic waves W in a state in which the constantvoltage or the constant current is applied are further provided, and theanalysis unit 22 generates the analysis image 31 on the basis of adetection signal from the reaction detection unit 5. In this way, theinspection of the packaged semiconductor device D can be performed withhigh accuracy by measuring change in resistance in the semiconductordevice D caused by the input of the ultrasonic waves W.

Further, in the ultrasonic inspection device 1, the pulse generator 4which inputs the driving signal to the ultrasonic transducer 2 andoutputs the reference signal corresponding to the driving signal isfurther provided, and the analysis unit 22 generates the analysis image31 on the basis of the detection signal and the reference signal. Theinspection accuracy of the packaged semiconductor device D can befurther enhanced by performing the lock-in detection on the basis of thereference signal.

Further, in the ultrasonic inspection device 1, the analysis unit 22generates the reflection image 32 on the basis of the detection signalfrom the receiver 13. The shape of the chip C in the semiconductordevice D can be acquired on the basis of the reflection image 32.Furthermore, it is also possible to detect physical abnormalities suchas separation of a circuit.

Further, in the ultrasonic inspection device 1, the analysis unit 22generates the superimposed image 33 in which the analysis image 31 andthe reflection image 32 are superimposed. In the superimposed image 33,since the analysis result from the analysis image 31 and the shape ofthe chip C in the semiconductor device D are superimposed, it is easy toidentify a position of a fault and the like.

The present invention is not limited to the above-described embodiment.In the above-described embodiment, a method of adjusting the focalposition of the ultrasonic waves W based on the peak of the timewaveform K is applied in a device which analyzes the reaction of thesemiconductor device D according to the input of the ultrasonic waves W,but the adjustment method may be applied as another method to the devicewhich analyzes the reaction of the semiconductor device. For example,the adjustment method may be applied to a device which analyzes thereaction of the semiconductor device by inputting a test pattern from atester.

REFERENCE SIGNS LIST

-   -   1 Ultrasonic inspection device    -   2 Ultrasonic transducer    -   3 Stage    -   4 Pulse generator (signal generation unit)    -   5 Reaction detection unit    -   10 Power supply device    -   13 Receiver (reflection detection unit)    -   21 Stage control unit    -   22 Analysis unit    -   31 Analysis image    -   32 Reflection image    -   33 Superimposed image    -   A Detection window    -   C Chip    -   D Semiconductor device    -   K Time waveform    -   P2 Peak    -   W Ultrasonic wave

1. An ultrasonic inspection device for inspection of a packagedsemiconductor device, comprising: an ultrasonic transducer configured tooutput ultrasonic waves to the semiconductor device; a reflectiondetector configured to detect reflected waves of the ultrasonic wavesreflected by the semiconductor device; a stage configured to move aposition of the semiconductor device relative to the ultrasonictransducer; a stage controller configured to control driving of thestage; and an analyzer configured to analyze a reaction of thesemiconductor device in accordance with an input of the ultrasonic wavesby the ultrasonic transducer, wherein the stage controller controls adistance between the semiconductor device and the ultrasonic transduceron the basis of a peak appearing in a time waveform of the reflectedwaves detected by the reflection detector.
 2. The ultrasonic inspectiondevice according to claim 1, wherein the stage controller controls thedistance between the semiconductor device and the ultrasonic transducerso that the peak of the time waveform is maximized.
 3. The ultrasonicinspection device according to claim 1, wherein the stage controllercontrols the distance between the semiconductor device and theultrasonic transducer on the basis of any one of peaks after a secondpeak which appear in the time waveform.
 4. The ultrasonic inspectiondevice according to claim 1, wherein the stage controller sets adetection window for the time waveform on the basis of packageinformation in the semiconductor device and detects the peak.
 5. Theultrasonic inspection device according to claim 1, further comprising: apower supplier configured to apply a constant voltage or a constantcurrent to the semiconductor device, and a reaction detector configuredto detect a current or a voltage of the semiconductor device inaccordance with input of the ultrasonic waves in a state in which theconstant voltage or the constant current is applied, wherein theanalyzer generates an analysis image on the basis of a detection signalfrom the reaction detector.
 6. The ultrasonic inspection deviceaccording to claim 5, further comprising a signal generation unitconfigured to input a driving signal to the ultrasonic transducer andoutput a reference signal corresponding to the driving signal, whereinthe analyzer generates the analysis image on the basis of the detectionsignal and the reference signal.
 7. The ultrasonic inspection deviceaccording to claim 5, wherein the analyzer generates a reflection imageon the basis of a detection signal from the reflection detector.
 8. Theultrasonic inspection device according to claim 7, wherein the analyzergenerates a superimposed image in which the analysis image and thereflection image are superimposed.
 9. An ultrasonic inspection methodwhich allows inspection of a packaged semiconductor device, comprising:an adjusting a focal position of ultrasonic waves output from anultrasonic transducer with respect to the semiconductor device; and ananalyzing a reaction of the semiconductor device in accordance withinput of the ultrasonic waves, wherein, in the adjusting, reflectedwaves of the ultrasonic waves reflected by the semiconductor device isdetected, and a distance between the semiconductor device and theultrasonic transducer is adjusted on the basis of a peak appearing in atime waveform of the reflected waves.
 10. The ultrasonic inspectionmethod according to claim 9, wherein, in the adjusting, the distancebetween the semiconductor device and the ultrasonic transducer isadjusted so that the peak of the time waveform is maximized.
 11. Theultrasonic inspection method according to claim 9, wherein, in theadjusting, the distance between the semiconductor device and theultrasonic transducer is adjusted on the basis of any one of peaks aftera second peak which appear in the time waveform.
 12. The ultrasonicinspection method according to claim 9, wherein, in the adjusting, adetection window for the time waveform is set on the basis of packageinformation in the semiconductor device, and the peak is detected.